Mill Valley is a city in Marin County, California, United States, located about 14 miles north of San Francisco via the Golden Gate Bridge. It is located on the western and northern shores of Richardson Bay. Beyond the flat coastal area and marshlands, it occupies narrow wooded canyons, mostly of second-growth redwoods, on the southeastern slopes of Mount Tamalpais.

Mill Valley is surrounded by hundreds of acres (hectares) of state, federal, and county park lands. In addition, there are many municipally maintained open-space reserves, parks, and coastal habitats which, when taken together, ensconce the city in a natural wilderness. This close and constant proximity to nature has left generations of Mill Valley residents with a strong sense of conservancy toward much of this natural environment. This unique cultural attitude, along with the many natural public spaces preserved within and around its borders, combine to form one of the main cultural cornerstones that has always defined Mill Valley.

Mill Valley maintains many recreational parks which often contain playgrounds and other designated areas specifically designed for playing various sports. Mill Valley is known for being a village with a strong artistic heritage. A visitor to downtown Mill Valley will discover many art galleries, open-air coffee shops, and other hallmarks of a thriving artistic community.

Public schools are managed by the Mill Valley School District. There are five elementary schools and one middle school, Mill Valley Middle School, a four-time winner of the California Distinguished School Award.